Now that scientists have discovered evidence of ancient life on Mars, can any sign of morning life on CBS be far behind?

For 40 years, CBS News has poked, prodded, retooled and morphed its 7 to 9 a.m. program without matching the success of NBC's "Today," ABC's "Good Morning America" or, more recently, such local shows as the Bay Area's "Mornings on 2."

All in all, the CBS morning news program has been repaired by more mechanics than a 1984 Jaguar, none of whom could wrench it into acceptable running condition.

"CBS has been kind of jinxed that in a cyclical business, there's been nothing cyclical about our competitive position in the morning," admits CBS News President Andrew Heyward.

On Monday, CBS will try again, with an inside-out approach contrived to satisfy affiliate stations in the Bay Area and other major television markets.

CBS will surrender most of the first hour, 7 to 8 a.m. weekdays, to affiliates that want to produce their own shows. The network will retain 8 to 9 a.m. for a revised "This Morning" program. It's a clever attempt to solve a delicate problem -- allowing affiliates to go their own way without network abandonment of the morning time period.

Tune in to KPIX at 7 a.m. Monday and you'll witness the birth of "Channel 5 This Morning," a daily hourlong program the station categorizes as a talk show, not a news show. KPIX will program about 32 minutes of the hour. CBS News will provide about 15 minutes of national cut-ins, and commercials will consume the balance.

Channel 5's Bill Schechner will be on hand for morning news briefs, and weathercaster Roberta Gonzalez will arrive from Chicago late next month. But mostly, "Channel 5 This Morning" will ride on the personality of its host, Marcia Brandwynne.

The show will be "wrapped around Marcia's personality," says KPIX news director Al Corral.

Brandwynne will eschew the conventional anchor desk in favor of an informal living-room set from which she promises to give viewers a free-form hour of chatter, interviews, commentary and laughter.

"I want to create a Bay Area morning gathering," Brandwynne said this week. "I can't even tell you what the show is going to end up being. We're just going to see."

Everyone at KPIX describes the program as a work in progress. But if "Channel 5 This Morning" sounds like a hybrid of entertainment and news, that fits Brandwynne's own background. After beginning her career as a news reporter and anchor in the Bay Area, Brandwynne has bounced back and forth between both worlds.

She was in TV news in Los Angeles and talk radio in Los Angeles and New York. She's been executive vice president of Carol Burnett's production company, worked with TV producer Norman Lear, helped develop feature films (including "Made in America" with Ted Danson and Whoopi Goldberg) and taught journalism at the University of Southern California.

The zigs and zags apparently don't trouble Brandwynne, who might rankle purists with her candid declaration that "television is an entertainment medium, whether it's news or not."

Brandwynne returned to the Bay Area last year to anchor KPIX's noon newscast with Schechner and fill in on the "Eyewitness News" evening broadcasts. Brandwynne and Schechner will continue anchoring the noon news; it's a collaboration she says she values, and she hopes to exploit Schechner's dry humor on the morning program.

"He's about my favorite person I've ever been on television with," Brandwynne said. "I hope I'm never alone. I'm a good tennis player, as somebody said once. I'm not a monologuist. I love interacting with people."

CBS News will offer its new "This Morning" show from 7 to 8 a.m. for stations that decline to produce their own programs, and a second hour of the network program will be seen on KPIX.

Harry Smith, who had been on "CBS This Morning" since 1987, and Paula Zahn, who joined the show in 1990, have been reassigned at CBS. The new network morning hosts, starting Monday, are former "CBS This Morning" weathercaster Mark McEwen, former "CBS This Morning" news reader Jane Robelot and former Miami news anchor Jose Diaz-Balart.

"I'm looking forward to people saying, 'Is it going to rain this weekend?' and I can say like everybody else, 'I don't know,' " he told reporters on the television press tour a few weeks ago in Pasadena.

Alterations in CBS' morning bloc reflect not only the network's prolonged failure in the time period, but also the increasing muscle of local stations. CBS is now owned and operated by Westinghouse, a company whose broadcasting history lay in local station ownership. In effect, the network was acquired by a group of its own affiliates, including KPIX.

No wonder most CBS affiliates feel they have nothing to lose in swapping the network's minuscule morning news ratings for an enterprising hour of their own.

Asked about his ratings expectations for "Channel 5 This Morning," news director Corral laughed and responded with a question of his own: "Did you see yesterday's numbers?"

No matter how tough the local competition from KTVU (Channel 2), it'll be pretty hard not to improve on a 1.2 rating.